Myokai F, Washio N, Asahara Y, Yamaai T, Tanda N, Ishikawa T, Aoki S, Kurihara H, Murayama Y, Saito T
Department of Periodontology, Okayama University Dental School, Japan.
Dev Dyn. 1995 Jan;202(1):80-90. doi: 10.1002/aja.1002020108.
It has been shown that mirror-image duplications of the zeugopodia and digits are formed when MRC-5 fibroblasts producing hepatocyte growth factor (HGF) are applied to the anterior region of the chick limb bud (Yonei et al. [1993] Dev. Biol. 160:246-253). To evaluate the role of HGF in limb development, we observed the expression pattern of the HGF gene using in situ hybridization. The HGF gene was expressed in the mesoderm of the limb bud and in the central core region of mandibular arch and maxillary processes at stages 17 to 24. When both wing and leg buds begin to extend distally, the HGF gene is expressed in the mesenchymal cells, but not in the ectodermal cells and somites. Concomitant with establishment of the apical ectodermal ridge, distal mesenchymal cells of the limb bud express the HGF gene intensely with a gradient higher in the distal region. The HGF expression is later confined to the ventral and subapical mesenchyme of the limb bud, although no signal is detectable in the apical and non-ridge ectoderm. However, signal for the c-met proto-oncogene encoding the HGF receptor is not detectable in the limb bud at stages 17 to 24. These results suggest that HGF produced in the limb mesoderm may be involved in initial induction and maintenance of the apical ectoderm during limb development.
研究表明，当将产生肝细胞生长因子（HGF）的MRC-5成纤维细胞应用于鸡胚肢芽的前部区域时，会形成zeugopodia和指（趾）的镜像重复（Yonei等人，[1993]《发育生物学》160:246 - 253）。为了评估HGF在肢体发育中的作用，我们使用原位杂交观察了HGF基因的表达模式。在第17至24阶段，HGF基因在肢芽的中胚层以及下颌弓和上颌突的中央核心区域表达。当翅芽和腿芽开始向远端延伸时，HGF基因在间充质细胞中表达，但在外胚层细胞和体节中不表达。伴随着顶端外胚层嵴的建立，肢芽的远端间充质细胞强烈表达HGF基因，在远端区域具有更高的梯度。HGF表达后来局限于肢芽的腹侧和亚顶端间充质，尽管在顶端和非嵴外胚层中未检测到信号。然而，在第17至24阶段的肢芽中未检测到编码HGF受体的c-met原癌基因的信号。这些结果表明，肢体中胚层产生的HGF可能参与肢体发育过程中顶端外胚层的初始诱导和维持。
